There is a need for a satisfactory pump which can be economically manufactured and which is capable of delivering quantities of liquid in the microliter range, to an accurate degree, as and when required. One area where such a need is felt is in medical applications, where accurate but very small doses of pharmaceuticals have to be delivered to a patient according to a regular or irregular timetable. A specific example is in the supply to a patient of an anticoagulant preparation in the treatment of thrombosis, or the supply to a patient of an insulin preparation in the treatment of diabetes. These quantities can be as small as 0.1 microliters. The design and manufacture of a micropump which can accurately deliver such a small but predetermined amount of liquid per stroke presents considerable difficulty.
Increasing attention is now being paid to the possibility of administering pharmaceuticals to patients from reservoirs of pharmaceuticals which have been physically implanted into the body. The pharmaceuticals can then be released close to the specific body region where their action is required, instead of being administered orally. They can be released from implants as and when the patient feels the need of medication, or according to a prearranged timetable or program, e.g. by external means operated externally of the body. The operation of such implant medications systems would be enhanced in some cases by the inclusion in the system of an implantable micropump, capable of delivering very small quantities of liquid per stroke and operable by means controlled from an implanted mechanism or from outside the body.